On this day in physics: 15 February 1786 - The Cat's Eye Nebula was discovered in 1786 by Astronomer William Herschel. Click for a fantastic image from NASA's astronomy picture of the day.
Word of the day- Amplitude- On a wave, the amplitude is the distance from the center of the wave to the highest point, known as the crest. The lowest point of the wave is known as the trough. So the amplitude is twice the distance from the crest to the trough. Think of a water wave on the beach, the crest of the wave is the highest point, which when it comes close to shore usually causes the wave to collapse, to the delight of beachgoers and surfers everywhere. The higher the amplitude, the larger the wave, and the more energy that it transfers, this is true of all waves. In radio signals, AM radio is referred to as amplitude modulation. In order to send your car radio the signal, the radio station varies the amplitude of the wave at a certain frequency in order to send the signal. As sort of a redaction to yesterday's FM explanation, the way the frequency modulation delivers the carrier signal is that the antenna is sensitive to changes in frequency to deliver the signal to your radio. (Sorry guys!) Think of amplitude modulation kind of delivering what you'd know as a longitudinal wave, changing the amplitude and keeping the same frequency, and frequency modulation as like a transverse wave of a spring, looking at the same amplitude, and of course modulating the frequency. There is a seriously excellent graphic illustrating this on the wikipedia entry for Frequency Modulation, so you can check that out here if you're so inclined.
Quote of the Day: "Arc, amplitude, and curvature sustain a similar relation to each other as time, motion, and velocity, or as volume, mass, and density." - Carl Frederich Gauss [Source]
Keywords: Cat's Eye, Nebula, Amplitude, Wave, Crest, Trough
